It's a great question.
As much as I love to have an opinion on everything, I didn't actually have anything to recommend. So I crowd sourced, asking my network of tech and startup GCs (as well as one law firm partner) if they had any ideas. I of course got back a few "you can't teach someone how to be business minded" sort of answers. But for those of you out there who still believe in the power of improving yourself through education, here's what our friends suggested:
The Hard Thing About Hard Things - Building a Business When There Are No Easy Answers [Ben Horowitz]
Good to Great - Why Some Companies Make the Leap...And Others Don't [Jim Collins]
Ogilvy on Advertising [David Ogilvy]
The Inside Counsel Revolution: Resolving the Partner-Guardian Tension [Ben W. Heineman, Jr.] ***this one was popular and made a few people's lists
Lawyering: A Realistic Approach to Legal Practice [James Freund]
How to Win Friends and Influence People [Dale Carnegie]
The Prince [Machiavelli]
The Generalist Counsel: How Leading General Counsel are Shaping Tomorrow's Companies [Prashat Dubey and Eva Kripalani]
Shoe Dog - A Memoir by the Creator of Nike [Phil Knight]
The Master Switch: The Rise and Fall of Information Empires [Tim Wu]
Capital in the Twenty-First Century [Thomas Piketty]
The Four - The Hidden DNA of Amazon, Apple, Facebook and Google [Scott Galloway]
Building an Outstanding Legal Team: Battle-Tested Strategies from a General Counsel [Bjarne P. Tellmann]
Traction: Get a Grip on Your Business [Gino Wickman]
Grit [Angela Duckworth]